1. Field of the Invention
The present invention relates generally to injection molding system controllers, and more specifically to mold and hot runner controllers.
2. Background Art
Injection molding systems are used to form objects of a type of plastic or resin, or other materials such as metals or powders. Typically, an injection molding system includes an injection molding machine that has an extruder, machine platens that may be connected by tie bars and a machine base. The machine platens are used to secure mold plates including the mold cavities and the mold cores. Each mold typically has two parts, a cold-half and a hot-half. During the injection molding process, the cold-half is mated with the hot-half to form the appropriate shape. The hot-half includes a hot runner system having a manifold and one or several hot runner nozzles that contain flow passages through which a melt stream reaches the mold cavity via a single or several mold gates. For optimal molding, the melt stream must remain within a fairly narrow window of operating processing parameters, such as temperature and pressure. For this reason, the cold-half and the hot-half of the mold typically include sensors for monitoring such physical properties of melt. For example, the hot-half typically includes appropriately positioned thermocouples to monitor the temperature at various locations such as along the flow path of the melt, for example.
Injection molding systems typically include at least one machine controller for monitoring and adjusting the most critical processing conditions, such as temperature or pressure, within the injection molding machine and sometimes in the mold. In some cases, there is a need for a separate hot runner or mold controller in addition to the machine controller. The hot runner controller is typically located on the machine shop floor by the injection molding machine and receives information from the sensors via cables linked to the mold and to the controller. To better control the characteristics of the melt in an injection molding system during processing, in a typical injection molding system, there are numerous zones that need to be separately monitored and adjusted in order for optimal molding to occur within each mold cavity. Therefore, each zone of a typical injection molding system has its own self-regulating closed-loop control.
Injection molding systems use microprocessor-based controllers for monitoring and adjusting processing conditions within the mold. A controller typically responds to the output of sensors placed at appropriate locations within the hot-half of the mold by sending a control signal to a device within the injection molding system that can vary the processing condition as requested by the control signal. For example, if a sensor in the mold reports that a certain zone of the mold is at too low of a temperature, the controller will respond by sending a control signal to the heating device that can then raise the temperature to the appropriate level for that zone.
In a typical injection molding control system, the mold sensors provide signals to the controller when reporting a processing condition of the mold. These signals are communicated from each sensor to the controller through wires and in an injection molding system with 32, 64, or 96 cavities, there could be hundreds of wires needed. In a typical injection molding system, the controller is set a distance away from the mold due to its typically large size. The number and size of cables required to carry the wires from the injection mold to the controller is cumbersome in that the cables need to run along the floor, under the floor, or above the floor creating spatial, storage, and machine access problems and inconvenience.
In addition to its typically large size, the controller of a typical injection molding system is also set a distance away from the mold to protect it from the high temperatures normally associated with the injection molding process. The heat generated from the injection molding process may possibly have an adverse effect on the performance and operability of the electronics within the controller, if the control module is attached to the injection mold itself. Known controllers that are attached to the mold require a cooling mechanism to prevent such adverse effects. Also, these controllers are totally dedicated and customized to the specific mold and hot runner system so they can move with the mold and the hot runner system from one machine to another. A new mold and a new hot runner system used to inject new articles will usually require a newly customized controller. Further, in a typical injection molding system, a controller and a customized hot runner system must be compatible and have compatible connections.